Trans-Alaska pipeline shifts, moving anchors

ANCHORAGE (AP) -- Officials with the Alyeska Pipeline Service Co. are trying to figure out why the trans-Alaska oil pipeline apparently shifted recently, moving several inches.

Inspectors with Alyeska, which operates the 800-mile line, discovered Friday that the pipeline shifted on the anchors that sit atop vertical supports. The pipeline remains intact and no oil was spilled.

The shift occurred near Pump Station Five, just south of the Brooks Range, along an above-ground section of the line. It's not known exactly when the movement occurred.

The anchor assemblies are designed to absorb movement of the line, but this latest movement was outside the normal range of motion, said Alyeska spokesman Mike Heatwole. The shift tripped seven anchors along a one-and-a-half mile section of the line.

Crews began making repairs to the anchor assemblies Monday and trying to determine why the shift occurred.

It was not the first time the pipeline has moved on its supports. In April 2000 a vapor pocket in the pipeline collapsed at Atigun Pass in the Brooks Range, causing a wave of pressure that moved the pipeline.

''I believe our initial review is that this is a different circumstance, but I don't want to speculate on causes. It could be for various other reasons that this occurred,'' Heatwole said.